Windows started the update automatically and restarted the computer without me being logged into it. After that, I tried turning on the poker server, but all times it failed.

First of all, it takes lots of time to load all the Data files, as there are more than 45 000 registered accounts. And after that, when I press Start, the program itself simply becomes Not Responding and I can't do anything about that. After some time, new window pop ups saying that Poker Mavens has stopped working and the program exits.

I am pretty sure, our hardware is capable of handling such server, as we have an Intel Xeon E3-1245V2, 32GB of RAM and 3 SSD drives working in RAID 1, so it is for sure not the error in the corrupted data by the drives.

Also, API seems to be barely working while the sever stays in the "Not Responding" state. Remote Administration works as well, and I can connect with the client, but no Ring Games, Tournaments or Logins are shown, everything is empty and without count on the Tabs. Also the table saying "Connection lost. Retrying..." pops up each few seconds.

Try using System Restore to get Windows back to it's previous state. Also turn off automatic updates for Windows and just preform them manually when you can take the poker server offline. Not sure about the other issues but try another reboot.

I don't know how, but after some time, the server kept being at "Not Responding" state, but didn't completely crash. After some time, it got back up to normal state, but API was still taking long time to respond, as well as other parts of the software too. But after some time without doing anything, everything started working normally again.

Well... It worked for like an hour and a half. Same again, everything is working like always, except for the API. It takes 4 to 6 seconds to respond. And I have no idea what might be the cause of this issue.